But I wish you good luck compiling a project that is not just old, it hasn't received any update from the last 12 years old -- let's not forget the amount of dependencies. I think this is not how technology works, but you can always believe in the opposite, of course

@n0ctilucient, don't get me wrong. I'm not judging you and your project. I'm just trying to tell you that it's not easy to compile projects that are very old because compilers, dependencies and system settings are changing constantly. I'll try to help you when I have time, OK?

However, if you can tell us why you need this old DE, maybe we can suggest something new that fits your demand. For example, I have a full OpenBox DE that takes just 9 MB and it's light and fast as hell, coming with a file manager and many other useful things.

Added in 1 hour 24 minutes 35 seconds:
So I found a static libfox 1.4, however when one of the FoxDE apps tries to link against it, I get this error:

g++: error: /usr/lib64/gcc/x86_64-slackware-linux/7.1.0/../../../../lib64/crti.o: No such file or directory
g++: error: /usr/lib64/gcc/x86_64-slackware-linux/7.1.0/crtbeginS.o: No such file or directory
g++: error: /usr/lib64/gcc/x86_64-slackware-linux/7.1.0/crtendS.o: No such file or directory
g++: error: /usr/lib64/gcc/x86_64-slackware-linux/7.1.0/../../../../lib64/crtn.o: No such file or directory

So either we fix this error (I have know idea how), or we compile libfox 1.4, which I tried and failed: